Law enforcement (LE) agencies of large cities in the United States often use a variety of personal radiation detectors (PRDs) for routine surveillance and first-responder radiological assessments. These PRDs are typically units that are worn on the duty belt of a law enforcement officer (LEO) with a readout of exposure rate and alarm capabilities to alert the officer if they are entering a high-radiation area.
These existing systems may be inconvenient for at least two reasons. First, when the PRD alarms, the LEO must divert their attention to the device, read, and interpret its output display, and determine appropriate next steps. This diversion of attention and having to hold an object, is quite dangerous for a law enforcement officer. Most officers will state that this scenario puts them at a great tactical disadvantage. Further, monitoring the PRD's readings is not only noticeable to others, but also reveals plain-clothed officers.
Second, the typical PRD has no means of detecting the location of the radiation source. With a PRD, the LEO reads its display for an assessment of exposure at their location, but the unit typically gives no information whatsoever so as to provide a means of locating the radiation source and, if co-located, the potential offenders. As such, without this directional or positional information the officer is generally unable to relocate civilians to a safe area and begin a search, if necessary.